On 12 Jan 2021 Shirlea Smith wrote on Sword-120: Seems that he was in Montreal in 1870 or whenever the Lovell's 1871 directory was put together, but he was not enumerated there for the 1871 Census. He shows up in Goderich in 1878, getting married in May. I wonder if it is possible to work backwards from the sighting in Goderich. Newspapers in Goderich in the earlier part of the 1870s?? Directories? Employment records of a railway? Does anyone have access?
Not sure if this is your Thomas but there is a record within the BaNQ Archives in Quebec -involves time period of 1877 to 1883. heres link
https://numerique.banq.qc.ca/patrimoine/details/52327/3215449?docsearchtext=Thomas%20S.%20Robertson
you maybe able to get more info by contacting BAnQ on their website by just giving the info that is on the right side of the page you viewed, click information and then send that info to someone thru the website contact section. see if they have anything else. Or another way is to search both names involved in the search box of BAnQ.
Also I just went into Library and Archives of Canada & typed in Thomas S Robertson. up popped 76 pages of documents, 1st one has to do with "railway". not sure how many of these pages may include info on him, but would be worth a looksee. Also try researching by using his wife(wives?) names and any other family members sometimes this will bring more results than searching their own names.. heres link to what I found in LAC BAC- https://www.bac-lac.gc.ca/eng/Search/Pages/results.aspx?k=,Thomas%20S%20Robertson#k=%2CThomas%20S%20Robertson